This invention relates generally to scintillation cameras used in nuclear medicine, and, more particularly, to nuclear camera apparatus for obtaining tomographic images.
In nuclear camera imaging, it has long been recognized that one can obtain improved image resolution and contrast by positioning the camera head as close to the organ of interest as possible. When performing planar imaging, it has been a simple matter to move the camera as close as possible to the patient to thereby allow minimum camera-to-organ distance. When performing tomographic imaging, on the other hand, the operator is not able to acquire the same proximity to the camera. That is, since the conventional tomographic camera system rotates the camera head in a circle around the longitudinal axis of the patient, the non-circular shaped cross section of the patient requires that the camera head be placed at a farther distance from the patient than desired when obtaining a coronal (front or back) view.
One approach for minimizing the patient-detector distance is that of moving the camera head in a non-circular, or generally oval path about the patient. This procedure is mechanically difficult when considering the substantial weight of a camera head. Further, even if one is able to construct a camera which will move its head in an oval pattern, it is difficult to include the flexibility to accommodate different-sized ovals so as to satisfactorily accommodate different-sized patients.
Another problem arises with the concept of moving the camera in an oval pattern around the patient. If the camera head is cantilevered from a longitudinally displaced position with respect to the patient, as it most commonly is, then any radial movement of the camera head which is necessary to obtain an oval path will also result in an associated axial movement of the camera with respect to the patient. This, in turn, tends to restrict the camera's field of view, since the part of the patient that the camera sees will vary as the rotation occurs. Although provision can be made to correct for the change in the detector axial position as the data is collected, this correction may result in a degradation of resolution. Further, it must be recognized that the organs of interest, such as the liver or the lungs, may not be entirely within the field of view during the entire camera rotation, thereby necessarily degrading the resolution of any resulting image.
It is therefore an object of the present invention to provide a nuclear imaging tomography system with improved image resolution and contrast.
Yet another object of the present invention is the provision in a nuclear imaging tomography system for minimizing the patient-detector distance as the camera is moved around the patient to obtain the various views for reconstruction.
Still another object of the present invention is the provision for a nuclear imaging tomography system which minimizes the patient-detector distance while maintaining a full field of view during the rotation around the patient.
Yet another object of the present invention is the provision for a nuclear imaging tomography system which is economical to manufacture and practical in use.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.